Early July, you'll likely be dealing with mosquitos no matter where you end up.
As for the hikes:
a) goes over Red Gap Pass, which is usually passable a little earlier than some of the other trail passes, but would still be iffy at best in early July. Poia Lake is one of my least-favorite campsites, but once you get past there the hike would improve considerably. See if you can get a current trail condition report on the pass once you arrive.
b) would be an excellent choice all around, I think. To make it more of a loop, you could look at hiking in to Elizabeth via Lee Ridge.
c) goes over Triple Divide Pass, which again might be problematic in early July. The last day, there'd be a fair amount of hiking through a burn area.
The Park Service used to try to open the HIghline on about July 1, but they're backed off of that goal in recent years, largely due to the danger involved. There's a chance the Highline will be open at the time of your visit, but I wouldn't necessarily count on it.
Mark